code: def get_table_names(self, handler):
      res = handler.get_tables()
      tables = res.data_frame
      assert (
          tables is not None
      ), "expected to have some tables in the db, but got None"
      assert (
          "table_name" in tables
      ), f"expected to get 'table_name' column in the response:\n{tables}"
      return list(tables["table_name"])
  
file_path: mindsdb/tests/handler_tests/test_postgres_handler.py
imports: import time
  import pytest
  import docker
  from mindsdb.integrations.handlers.postgres_handler.postgres_handler import PostgresHandler
  from mindsdb.api.executor.data_types.response_type import RESPONSE_TYPE
label_desc: Use image node_id 10 for calling the TestPostgresHandler obj's underlying member method code with example usage: obj.get_table_names(handler) and returns: list